Cardiac Muscle Tissue

Introduction to the Cardiac Muscle Tissue:

Cardiac muscle cells (cardiocytes or cardiac myocytes) make up the myocardium portion of the heart wall.

The cardiac muscle cell or fiber.

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They are relatively short, branched fibers that measure approximately 10 to 10 micrometers in diameter and 50 to 100 micrometers in length.

The cardiac muscle tissue consists of short branched fibers.

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Typically each cardiac myocyte contains a single nucleus, which is centrally positioned.

The nucleus of a cardiac myocyte.

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Thick and thin myofilaments are present and organized into myofibrils.

Their overlapping arrangements creates alternating dark (A) and light (I) bands or striations, similar to those seen in skeletal muscle tissue.

The striations of the myofibrils.

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Sarcoplasmic reticulum tubules surround the myofibrils. However, they are not well organised and do not have terminal cisternae. T-tubules are also present but run along the Z-discs (instead of the myofilament overlap zones).

The mitochondria in the cardiac myocytes are large and numerous. They supply the ATP for repeated contractions of the heart.

Unlike other types of muscle tissue, cardiac myocytes are joined end to end by intercalated discs.